At work last week, I spent some time helping to write a small tool that would performance and capacity test our applications. We thought it would be great if at the end of the test run, the tool would generate a series of graphs to display the trends of certain key metrics over the course of the test. A quick search of the web for charting tools lead me to the Google Chart API.

The Google Chart API is a very slick tool for generating all sorts of graphs. You build the graphs by specifying all of the data for the graph, the graph type, and the graph metadata in the URL. The URLs get a little nasty, but in all fairness, there is a ton of information being conveyed in the URL. So, it’s going to be nasty no matter what you do.

My only concern was relying on an external web service to generate the graphs. Since this is just a development tool, it wouldn’t be the end of the world if the Google Chart API went away. We would simply adjust the tool to use some other graphing library. And, as for all of the old charts from previous runs…we wouldn’t want all of those graphs simply “disappearing”. So, instead of using the Google Chart API URL directly in the reports, I do a wget on the URL, and store the image on my file system. I then reference that local image in the reports.

All in all, the Google Chart API is a very slick, easy to use tool. I’d recommend checking it out next time you need to quickly throw together some graphs.